Explore the vast range of titles available.

In this paper, a novel modified whale optimization algorithm based on Tent chaos map and tournament selection strategy (MWOA) was presented. The aim of the improved algorithm is to reduce the possibility of the standard whale algorithm falling into local optimal. During the initialization of the population, in order to increase population diversity and randomness, MWOA cites the Tent chaos map. In the optimization process, in order to improve the development ability of the standard algorithm, the tournament selection strategy was employed to improve the algorithm accuracy. Numerical simulation and example calculation results show that the improved algorithm is superior to the standard WOA algorithm. The improved method provides a new method for truss structure optimization.

Uncertainties over future climatic conditions pose significant challenges when selecting appropriate conservation strategies for heritage sites. Choosing effective strategies is especially important for earthen heritage sites located in dryland regions, as many are experiencing rapid environmentally-driven deterioration. We use a newly developed cellular automaton model (ViSTA-HD), to evaluate the environmental deterioration risk, over a 100-year period, under a range of potential climate and conservation scenarios. Results show increased wind velocities could substantially increase the overall deterioration risk, implying the need for wind-reducing conservation strategies. In contrast, predicted increases in rainfall are not likely to increase the overall deterioration risk, despite greater risk of rain-driven deterioration features. Of the four conservation strategies tested in our model, deterioration risk under all climatic scenarios was best reduced by increasing the coverage of natural, randomly-distributed vegetation to 80%. We suggest this approach could be an appropriate long-term conservation strategy for other earthen sites in dryland regions.

Hosting precious superb murals and painted sculptures from the fourth to the fourteenth century, the UNESCO word heritage site Mogao Grottoes are one of the most famous sites of Buddhist art. Although several reinforcement projects had been implemented, frequent rockfalls originated from the slope atop the cliff of Mogao Grottoes can be observed, representing a significant risk to both relics and tourists. Therefore, it is important to assess the rockfall hazard of the slope of Mogao Grottoes for the preventive protection as well as to inform future management decisions. In this study, rockfall hazard of the slope of Mogao Grottoes was assessed by using Analytic Hierarchy Process (AHP), Fuzzy-AHP (F-AHP) and AHP-TOPSIS methods and then the performances were evaluated by receiver operating characteristic curve (ROC) and area under curve (AUC). To execute these methods, a high-resolution digital surface model was first captured through UAV digital photogrammetry technology without contact. Belonging to four hazard levels (Very high, high, low and very low), the slope was divided into 10 units based on the slope topography. The hazard assessment result shows that 80% of the total slope units are at low rockfall hazard level and 20% slope units are at very high/high level, respectively. Moreover, loose debris and rainfall are confirmed as the most active causative factors. The result of AUC, ROC and recorded rockfall events reveal that the F-AHP is the most suitable method. Besides, this study also holds the potential applications of the F-AHP in the rockfall assessment for many other grottoes carved in conglomerate strata in Dunhuang.

Based on the research results and practical engineering experience pertaining to the protection and reinforcement of the cliff of the Mogao Grottoes in Dunhuang, China, this paper presents a method that is mainly based on the analytic hierarchy process (AHP) to evaluate the preservation state and risk of the Mogao cliff, a means that numerical simulation was conducted to quantitatively evaluate the stability and effectiveness of protective measures for the Mogao cliff, a set of reinforcement methods which integrate the key protection techniques based on propping, anchoring, grouting, and anti-weathering and the quality control measures based on assessing their effectiveness for surrounding rocks of the grottoes, and a set of methods for monitoring and warning based on risk theory throughout the entire reinforcement process. The four above-mentioned techniques complement and support with each other, and every stage is based on research. Additionally, the protection and reinforcement concepts implemented at the Mogao cliff are summarized in this paper. Finally, preventive protection and reinforcement techniques for sandy conglomerate grottoes were established based on the research, evaluation, calculation, and monitoring. The techniques presented in this paper can be used as a theoretical foundation and provide technical guidance for the protection and reinforcement of similar cultural heritage sites all over the world.

Earthen sites are important remains of past human societies. Weather-resistant measures comprise a major part of conservation efforts for earthen sites. Marked advancements in weather-resistant techniques have been made in recent years. Earthen sites are characterised by large numbers, large scales, various types, complex compositions, and diverse existing environments. Weather-resistant measures differ significantly in their environmental adaptability. The environmental adaptability of weather-resistant measures severely restricts further development and popularisation of weather-resistant technology at earthen sites. Based on the environmental and weathering characteristics of existing earthen sites in China, the consolidation and failure mechanisms of several weather-resistant measures (penetrating consolidation, sacrificial layers, soft capping, protective structures, and backfilling protection) were examined. The potential areas to increase the success of the different weather-resistant measures were obtained combined with the characteristics of various environmental boundaries.

The Dunhuang Mogao Grottoes are a significant cultural heritage site in the Silk Road, famous for its wonderful murals and statues. The rainfall causes the changes of humidity in the caves, which can easily activate the salts diseases of murals. In order to prevent the deterioration of the murals, the environmental monitoring tests were conducted to analyze the microclimate changes of the cave in rainfall weather, and proposed the risk prevention measures and suggestions. The results indicate that the temperature of caves has small change, but the humidity shows a clear trend of increase. The humidity and the duration of high humidity increases with the increase of the rainfall grade and frequency. The optimal starting time for environment control in the cave is when aatm and acave are consistent, and the relative humidity is controlled below 62%. The caves with lower layer, larger degree of openness and small volume are most vulnerable to water vapour diffusion. The environment monitoring should pay more attention to the continuous rainfall weather and the vulnerable caves. The research has great significance for the prevention of ancient mural deterioration.

Natural hydraulic lime (NHL) can be used as an inorganic cementitious material, as it exhibits low shrinkage, salt-alkali resistance, moderate strength, and good durability with cultural relics. There has been increasing interest in NHL, as it is considered an appropriate material for the restoration and reinforcement of architectural cultural relics. In this study, limestone and potassium feldspar were mixed and calcined at different ratios and high temperatures, and artificial hydraulic lime (HL) was produced. According to the X-ray diffraction (XRD) results, the resulting products after high-temperature calcination were mainly composed of calcium oxide, dicalcium silicate (C2S), and dicalcium aluminosilicate (C2AS). As a compromise, when potassium feldspar accounted for 30% of the total mass, HL contains a more suitable air-hardening component and hydraulic component. Scanning electron microscope (SEM) and Energy Dispersive Spectrometer (EDS) analyses show that the phases of calcium carbonate (CaCO3) and hydrated calcium silicate (C-S-H) gradually increased with prolonged curing time for HL. To study the partial mechanical properties and durability of HL, a comparison was made with NHL. The mechanical properties were investigated with the flexural and compressive strengths and shrinkage. The results show that HL has higher strength than NHL, but NHL has smaller shrinkage. Accelerated aging tests indicated that HL and NHL5 led to higher resistance to water immersion, fluctuations in temperature and humidity, sulphate decay, an alkali environment, and frost–thaw action than NHL2. HL has excellent mechanical properties and durability and can be considered a conservation material for stone relics in the future.

Cracking of asphalt pavement is mostly caused by the mixed fracture of asphalt concrete. Determining a simple, repeatable, and accurate method is necessary for evaluating the fracture resistance of asphalt concrete. To explore the mixed fracture performance of asphalt concrete and determine the feasibility of different semicircular bend methods, the mixed fracture performances of asphalt concrete at medium and low temperatures were measured. The mixed fracture modes were realized through changing the position of the support and notch or changing the notch angle. After that, the crack propagating characteristics, crack initiation angle, and fracture toughness were analyzed. Results show that temperature has a significant impact on the fracture path, and crack initiation angle at low temperature follows the generalized maximum tangential stress (GMTS) theory. The measured fracture toughness ratios are lower than the theoretical value of GMTS criterion, but the established empirical model has higher accuracy. In the semicircular bend method, changing the positions of the support and notch is stable and repeatable. Therefore, this method may be preferred to evaluate the mixed fracture performance of asphalt concrete in the future.

The Mogao Grottoes are among the most famous sites on the World Heritage list. Several large-scale preservation projects were implemented in 1962, 1982, and 2008, respectively, to improve their preservation conditions. According to field investigation and assessment in recent years, the cliff is stable on the whole because of the reinforcement projects. Among them, there are still 42 potentially dangerous bodies, which may not be stable in some conditions. For the purpose of building the monitoring and early warning system and the long-term preventive preservation of the Mogao Grottoes, an innovative analytical method based on the Analytic Hierarchy Process (AHP) and Fuzzy-AHP was applied to assess the hazard of potentially dangerous bodies within the cliff. Firstly, the hazard was classified into six groups: very high, high, moderate, low, very low, and no hazard, in this study. Secondly, the AHP method was applied to calculate the impact index of each causative factor, and then the hazard assessment of dangerous bodies was made based on statistical analysis. Finally, the Fuzzy-AHP method was applied to calculate the correlation of each factor and determine the comprehensive hazard class. The results indicate that Fuzzy-AHP seems to be more accurate than AHP in hazard assessment. Meanwhile, there is a very high risk body that can threaten 10 caves, three high risk bodies that can threaten 13 caves, and 15 moderate risk bodies can threaten 69 caves in total, while the remaining bodies are defined as low or very low grades. Overall, the results of this study provide much data and a theoretical model in the construction of a monitoring and early warning system currently. Furthermore, the new numerical simulation method also holds the potential application to assess the hazards of other types of heritage sites.